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a-level biology > 3.1.1 Exchange Surfaces > Flashcards

3.1.1 Exchange Surfaces Flashcards

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AP® Biology flashcards
1
Q

what do living organisms need to keep them alive

A

oxygen, water, glucose, amino acids, minerals

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2
Q

what do living organisms need to get rid of

A

carbon dioxide, urea, creatinine

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3
Q

factors that affect the need for an exchange system

A

size, SA:volume, diffusion distance
metabolic rate
endotherm/ectotherm

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4
Q

features of an efficient exchange surface

A

high surface area - max. molecules can diffuse per unit time
thin cell walls - short diffusion distance, faster rate
good blood supply/ ventilation - maintains steep conc. gradient
moist - enables gases to dissolve + cells protected from drying out
permeable - gases can diffuse through cell membrane

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5
Q

why do smaller organisms have a lower oxygen demand

A

smaller organisms = lower metabolic activity, low demand for oxygen

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6
Q

the main function of surfactant

A

lowers surface tension at the air/liquid interface within the alveoli to stop the walls from sticking together and collapsing during inhalation

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7
Q

mechanism of breathing: ventilating the lungs - inspiration

A

ACTIVE
external intercostals: contract
ribs move: up and out
diaphragm: contracts
diaphragm moves: down
diaphragm shape: flattens
thorax volume: increases
thorax pressure: decreases
air: drawn in, enters
internal intercostals: relax
elastic fibres: stretch

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8
Q

mechanism of breathing: ventilating the lungs - expiration

A

PASSIVE
external intercostals: relax
ribs move: down and in
diaphragm: relax
diaphragm moves: up
diaphragm shape: domed
thorax volume: decreases
thorax pressure: increases
air: expelled, leaves
internal intercostals: relax
elastic fibres: recoil to expel air

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9
Q

cartilage is found in

A

trachea - c-shaped rings
bronchus - plates

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10
Q

goblet cells are found in

A

trachea
bronchus

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11
Q

ciliated cells are found in

A

trachea
bronchus
bronchioles

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12
Q

smooth muscle is found in

A

trachea
bronchus
bronchioles

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13
Q

elastic fibres are found in

A

trachea
bronchus
bronchioles
alveolus

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14
Q

squamous epithelium is found in

A

alveolus

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15
Q

function of cartilage

A

strong - prevents collapse of trachea and bronchus
flexible- trachea and bronchi bend/extend
c-shaped rings - oesphagus can expand behind

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16
Q

function of goblet cells

A

secrete mucus- contains glycoproteins, traps pathogens

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17
Q

function of ciliated cells

A

hair like projections beat to waft mucus up the airway

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18
Q

function of smooth muscle

A

contracts - constricts/ narrows airway e.g. if there is a harmful substance in the air
relaxes - dilate airway to increase air flow to alveoli

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19
Q

function of elastic fibers

A

bronchioles- when smooth muscle contracts, elastic fibers stretch. when smooth muscle relaxes, elastic fibers recoil
alveoli- stretch to allow alveoli to expand. recoil to expel air. prevents bursting during inhalation

20
Q

function of squamous epithelium

A

thin, flattened cells - short diffusion distance = increased rate of gaseous exchange

21
Q

why is a nose clip worn when using a spirometer

A

to prevent the subject from breathing via the nose

22
Q

how does a spirometer work

A

breathe out into tank - upper half rises
breathe in from tank - upper half falls
a tracemarker is attached to mobile upper half connected to kymograph which records changes in oxygen

23
Q

why does total volume in tank slowly decline

A

the subject uses up oxygen from tank due to gas exchange in alveolus - left in dead space

24
Q

why is soda lime used in spirometer

A

soda lime absorbs carbon dioxide that is exhaled

25
Q

why does exhaled air contain oxygen

A

some inhaled air does not reach the alveolus for gas exchange to occur

26
Q

tidal volume

A

volume of air that flows in and out of the lungs with each breath during quiet breathing - usually measured at rest

27
Q

vital capacity

A

maximum volume of air that can be moved by the lungs in one breathe
strongest possible exhalation followed by strongest possible inhalation

28
Q

inspiratory reserve volume

A

maximum amount of air inspired in excess of the tidal volume - a normal inhalation

29
Q

expiratory reserve volume

A

maximum amount of air expired in excess of the tidal volume

30
Q

residual volume

A

volume left in lungs after maximum forced expiration

31
Q

total lung capacity

A

total air in lungs after maximum inhalation
total volume lungs can hold

32
Q

total air breathed per minute

A

tidal volume x breathing rate

33
Q

how might athletic training affect the condition of the lungs

A

more efficient lungs - improved network of pulmonary capillaries so more oxygen is taken up
slightly increases lung volume
increase in alveoli size
increased strength in muscles - can breathe in more air for longer periods of time
faster breathing rate - more oxygen produced
higher tidal volume

34
Q

why do fish have an exchange system

A

multicellular, move around: fairly high metabolic rate
ectotherms: cannot increase metabolic rate to maintain temperature, lower oxygen demand
fairly large - small SA:V ratio: large diffusion distance so cannot rely on simple diffusion alone
**water is thicker + denser than air: **more energy req. to cross gas exchange surfaces

35
Q

structure of fish gills in bony fish

A

series of gills on each side of the head
each gill arch attaches to 2 rows of filaments, 1 row of gill rakers
rows of lamellae in filaments
lamellae surface consists of a single layer of flattened cells that cover a vast network of capillaries

36
Q

gill rakers

A

made of bone or cartilage
prevents food particles reaching filaments
prevents obstruction of gas exchange

37
Q

how does the structure of the gills relate to their function

A

lots of filaments/lamellae: provide large SA
filaments + lamellae have thin walls: short diffusion distance
filaments + lamellae increase rate of diffusion of oxygen and carbon dioxide
filament tips overlap: increases resistance to flow of water = gives time for diffusion of gases
good blood supply via capillary network in capillaries in lamellae: maintains steep concentration gradient
counter current flow of blood and water: maintains concentration gradient across full length of gill

38
Q

counter current system of blood and water flow

A

blood and water flow in opposite directions
ensures concentration of oxygen in water is always higher than concentration of oxygen in the blood
concentration gradient can be maintained
more oxygen will diffuse into the blood

39
Q

ventilation in a bony fish: inspiration

A

mouth opens, operculum closed
buccal cavity floor lowers (muscles req. - ATP)
buccal cavity: pressure decreases, volume increases
water flows in via mouth down a pressure gradient
sides of opercular cavity bulge outwards (muscles req. - ATP)
opercular cavity: pressure decreases, volume increases
mouth closes, buccal cavity floor rises
buccal cavity: volume decreases, pressure increases
pressure in buccal cavity > pressure in opercular cavity
water forced to flow over gills, down pressure gradient

40
Q

ventilation in a bony fish: expiration

A

sides of opercular cavity move inwards
operculum opens
water flows in one direction over gills and is expelled

41
Q

why do insects have an exchange system

A

fairly active + multicellular: certain oxygen demands
tough exoskeleton: impermeable to gases no exchange via skin
**small - large SA:V ratio: ** short diffusion distance, can rely on simple diffusion

42
Q

tracheal system of an insect

A

spiracle: allows air to enter the insect
tracheae: have rigid rings of cartilage to keep it open
muscle fibres: the site of gas exchange

43
Q

function of tracheae

A

held open byb citin
enables carbon dioxide and oxygen to diffuse down

44
Q

function of trachioles

A

lots of trachioles increases SA
moist lining for gases to dissolve
lots of tracheal fluid at the end of trachiole which oxygen diffuses through

45
Q

when insects are active

A

muscles anaerobically respire to produce lactic acid
decreases water potential - drawing tracheal fluid into muscles by osmosis
more air is drawn in
higher surface area of the walls exposed for diffusion
rate of diffusion increases

a-level biology (26 decks)

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